Search results

Filter

Filetype

Your search for "*" yielded 528650 hits

Optoelectronic implementation of multilayer neural networks in a single photorefractive crystal

We present a novel, versatile optoelectronic neural network architecture for implementing supervised learning algorithms in photorefractive materials. The system is based on spatial multiplexing rather than the more commonly used angular multiplexing of the interconnect gratings. This simple, single-crystal architecture implements a variety of multilayer supervised learning algorithms including me

Test-retest repeatability of human speech biomarkers from static and real-time dynamic magnetic resonance imaging

Static anatomical and real-time dynamic magnetic resonance imaging (RT-MRI) of the upper airway is a valuable method for studying speech production in research and clinical settings. The test-retest repeatability of quantitative imaging biomarkers is an important parameter, since it limits the effect sizes and intragroup differences that can be studied. Therefore, this study aims to present a fram

The complex langevin equation and Monte Carlo simulations of actions with static charges

We explore the possibilities of using the complex Langevin equation to Monte Carlo generate configurations of gauge theories with static charges present in the action. Successful results are obtained for systems that possess nontrivial saddle-point (classical) solutions. For that reason the algorithm works impressively for two-dimensional U(1) in the entire β-range whereas for three- and four-dime

No title

From the 1880s until the ban of this practice in the 1970s, German vacationers built sandcastles, some of which were artfully decorated and awarded prizes in competitions by the spa administrations. Research regards this as a manifestation of a ‘typical German’ national character. The article counters this approach with an interpretation that understands sandcastles as metaphors for typical charac

Langevin simulations of configurations with static charges

By using the Langevin equation with complex action it is possible to generate (complex) configurations in the charged sector of gauge theories. We test the algorithm in the case of two-dimensional U(1) gauge theory and are able to measure the string tension with great precision and modest use of computer time for a separation of the charged particles where a conventional Wilson loop would have a v

Direct observation of string vibrations in three-dimensional compact QED

Three-dimensional compact U(1) is studied on a 16×32×16 lattice with emphasis on roughening around the crossover region. Configurations including two static charges are generated using the dual formulation of the theory. In this way the flux patterns between the charges are mapped out. Very convincing evidence for roughening is found. In particular we show that the average transverse spread of the

Finite-size effects for lattice glueball masses

We have measured the lattice size dependence of the lightest glueball mass in SU(2) and SU(3) gauge theory at =2.2 and 2.3 [SU(2)] and =6.0 [SU(3)]. We observe an increase in the glueball mass when the lattice size shrinks below a critical value. The magnitude of this length scale, which we interpret as the physical size of the glueball, is roughly the same for SU(2) and SU(3) when expressed in un

Magnetic resonance imaging quantification of left ventricular dysfunction following coronary microembolization

Microembolization is common after coronary interventions, and therefore this MRI study aimed to quantify the effect of coronary microembolization on left ventricular (LV) function. The left anterior descending artery (LAD) was selectively catheterized in an XMR suite (Philips Medical Systems, Best, The Netherlands) in eight pigs to deliver MR contrast media to measure the LAD territory using first

String model potentials and lattice gauge theories

The static potentials from bosonic string models are examined to the two-loop level. Available MC data for 4-dimensional SU(3) are in approximate agreement with the universal leading order predictions but fail to reproduce the Nambu string when the two-loop terms are included in the analysis. We also confront Nambu string model predictions for Tc σ with SU(2), SU(3) and SU(N → ∞) MC data. In the S

Stochastic confinement and dimensional reduction. (I). Four-dimensional SU(2) lattice gauge theory

By Monte Carlo calculations on a 124 lattice we investigate four-dimensional SU(2) lattice gauge theory with respect to the conjecture that at large distances this theory reduces approximately to two-dimensional SU(2) lattice gauge theory. We find good numerical evidence for this conjecture. As a by-product we also measure the SU(2) string tension and find reasonable agreement with scaling. The "a

The axial anomaly and the lattice Dirac sea

In the hamiltonian formulation of fermions coupled to external gauge fields, the axial anomaly has a simple physical interpretation in terms of level shifting at the top of the Dirac sea. We apply this formalism to lattice QED in 1 + 1 and 3 + 1 dimensions, in order to study how the lattice regulation and small fermion mass affect the picture. For a simple choice of the E and B fields, it is possi

Hadronic production of glueballs

Cross sections for glueball production in hadron-induced reactions are estimated using the gluon-gluon fusion mechanism. For pp → θ(1700, JPC = 2++)X one finds σθ ∼ 2-10 mb in ISR-collider energy range. This cross section should give a clean experimental signal given the substantial KK decay mode observed in ψ → γθ.

Multidetector computed tomography for characterization of calcium deposits in reperfused myocardial infarction

Background: Calcium overload is a major cause of reperfusion myocardial injury. Multidetector computed tomography (MDCT) has been previously used in visualizing coronary artery calcium, but not calcium deposits in reperfused infarction. Purpose: To assess the ability of MDCT to 1) noninvasively visualize and characterize calcium deposits in reperfused infarcts, and 2) monitor regional wall swellin

Strings and SU(3) lattice gauge theory

Recent SU(3) lattice Monte Carlo data (244 and 164) are analyzed in terms of a simple string model. Good agreement is found. Observed similarities between SU(3) and three-dimensional SU(2) indicate that the string theory is indeed an effective one.